Answer this question truthfully
### Question: What causes Pleural empyema?
### Response: Empyema is usually caused by an infection that spreads from the lung. It leads to a buildup of pus in the pleural space.
There can be a pint or more of infected fluid. This fluid puts pressure on the lungs.
Risk factors include:
Bacterial pneumonia. Chest surgery. Lung abscess. Trauma or injury to the chest.
In rare cases, empyema can occur after a needle is inserted through the chest wall to draw off fluid in the pleural space for medical diagnosis or treatment (thoracentesis).